The important property of magnesium hydroxide activity
The activity is not only an important physical and chemical property of magnesium hydroxide, but also an important index to measure magnesium oxide used in rubber industry. In other words, the heavy substance is pure MgO, while the light substance is xMgO · yMg(OH)2, I .e., basic magnesium oxide. Among them, the percentage of light magnesium oxide plays an important role in the activity.
activity is not onlyMagnesium hydroxideImportant physical and chemical properties, or an important indicator to measure the rubber industry with magnesium oxide. In other words, the heavy substance is pure MgO, while the light substance is xMgO · yMg(OH)2, I .e., basic magnesium oxide. Among them, the percentage of light magnesium oxide plays an important role in the activity.
Generally speaking, high activity magnesium oxide is prepared by decomposing basic magnesium carbonate at low temperature for a long time. The furnace structure is special, the energy consumption is high, and the apparent specific volume of the product is also large. In addition, highly active magnesium oxide having an iodine absorption value higher than 170mg I2/g MgO is also prepared from light magnesium oxide using microwave radiation. The apparent specific volume of the highly active magnesium oxide is as small as 2.5-3.3 ml/g.
Active magnesium oxide is mainly used for butyl rubber, chloroprene rubber, fluorine rubber, nitrile rubber activator and accelerator, or paint, adhesive, plastic and other products one of the main additives. With the development of science and technology and economy, the active magnesium oxide has been more and more widely used, and the requirement of product activity is more and more diversified.
There are many methods of producing magnesium oxide in China, such as seawater-lime method, brine-soda ash method, brine-carbon ammonia method, dolomite, magnesite-carbonization method, etc. Regardless of the production method, the activity of magnesium oxide is related to the production process. There are many factors affecting the activity, such as the internal defects of the lattice, the specific surface area, the production method and so on. Taking the brine-soda ash method as an example, the activity of magnesium oxide has a great relationship with the reaction temperature, pyrolysis temperature, reaction concentration (soda ash, brine), pressure, water control, and dehydration time after pyrolysis.
However, the control of the activity of magnesium oxide is mainly in the calcination process of the intermediate magnesium carbonate. Calcination at 600-700°C can produce highly active magnesium oxide. At 650°C, the maximum activity occurs, the temperature of the maximum activity depends on the heating time and the heating rate, especially the temperature, slow and continuous heating can provide the maximum activity. The lattice of new living magnesium oxide is compact, has a high specific surface area, and is porous. The maintenance of the magnesium carbonate composition constitutes a high activity. Further heating will reduce the surface area good porosity, internal structure hungry will occur sintering phenomenon. At relatively high temperatures, dead-burned magnesium oxide is produced. The decomposition kinetics verify that this process starts outside the crystal; the thermodynamic interpretation of the nature of the active magnesium oxide is a balance between the active mass rate produced and the sintered magnesium oxide. Calcining basic magnesium carbonate at 650°C produces extremely active magnesium oxide with a specific surface area of about 100 m2/g. At 700°C, all of the magnesium oxide has formed; above 700°C, the porous structure begins to shrink and the total area decreases. Secondly, when the oxide reaches the maximum amount, the specific surface area also reaches the maximum amount.
The results show that the calcination temperature has an effect on the activity of magnesium oxide. Calcination temperature, temperature rise rate and residence time have a great influence on the continuous decomposition of carbonate. At 700 ℃, there will be a turning point of the maximum rate, and the residence speed and time are related to the surface area of magnesium oxide. With the increase of temperature, at 900-1000 ℃, calcining basic magnesium carbonate produces low activity magnesium oxide.
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Zhongke Flame Retardant Organization Watches 20 Closing Ceremonies
On the morning of October 22, 2022, members of Zhongke Flame Retardant New Materials Co., Ltd. watched the closing ceremony of the 20th Congress under the leadership of General Manager Wang Ligui.
Everyone knows that there are two common flame retardants. Today we are going to talk about only one of them. Aluminum hydroxide flame retardant is an environmentally friendly halogen-free flame retardant, which can be widely used in fabrics, wood, plastics, and rubber., Polyurethane and other industries have ideal flame retardant effect. In the process of industrial application, it is found that flame retardant failure occurs when aluminum hydroxide flame retardant is added. The following are the reasons for the failure of aluminum hydroxide flame retardant, how to prevent it, how to deal with the operation, and restore the original function.
As a flame retardant, magnesium hydroxide also need to improve what aspects?
When it comes to flame retardants, everyone is familiar with them. Although we usually have less contact with them, we can know what they are used for from the name. Have to talk about magnesium hydroxide, we all know that its main presentation state is a granular, at present, the market sales of magnesium hydroxide particle size is larger, part of the commodity particle size up to tens of microns, immediately used as a flame retardant, poor dispersion, the physical properties of raw materials greater harm. In industrial production, physical grinding methods are generally used to reduce the particle size to 1 micron. The surface of magnesium hydroxide has high polarity and is easy to agglomerate. As the compatibility of refractory materials and polymer substrates, it not only reduces its flame retardant grade, but also causes more serious harm to the physical properties of raw materials.
Hefei Zhongke Flame Retardant New Material Co., Ltd
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